Landing Dynamic and Key Parameter Estimations of a Landing Mechanism to Asteroid with Soft Surface

Zhijun Zhao,JingDong Zhao,Hong Liu 한국항공우주학회 2013 International Journal of Aeronautical and Space Sc Vol.14 No.3

It is of great significance to utilize a landing mechanism to explore an asteroid. A landing mechanism named ALISE (Asteroid Landing and In Situ Exploring) for asteroid with soft surface is presented. The landing dynamic in the first turning stage, which represents the landing performance of the landing mechanism, is built by a Lagrange equation. Three key parameters can be found influencing the landing performance: the retro-rocket thrust T, damping element damping c₁, and cardan element damping c₂. In this paper, the retro-rocket thrust T is solved with considering that the landing mechanism has no overturning in extreme landing conditions. The damping element damping c₁ is solved by a simplified dynamic model. After solving the parameters T and c₁, the cardan element damping c₂ is calculated using the landing dynamic model, which is built by Lagrange equation. The validities of these three key parameters are tested by simulation. The results show a stable landing, when landing with the three estimated parameters T, c₁, and c₂. Therefore, the landing dynamic model and methods to estimate key parameters are reasonable, and are useful for guiding the design of the landing mechanism.

Landing Dynamic and Key Parameter Estimations of a Landing Mechanism to Asteroid with Soft Surface

Zhao, Zhijun,Zhao, JingDong,Liu, Hong The Korean Society for Aeronautical and Space Scie 2013 International Journal of Aeronautical and Space Sc Vol.14 No.3

It is of great significance to utilize a landing mechanism to explore an asteroid. A landing mechanism named ALISE (Asteroid Landing and In Situ Exploring) for asteroid with soft surface is presented. The landing dynamic in the first turning stage, which represents the landing performance of the landing mechanism, is built by a Lagrange equation. Three key parameters can be found influencing the landing performance: the retro-rocket thrust T, damping element damping $c_1$, and cardan element damping $c_2$. In this paper, the retro-rocket thrust T is solved with considering that the landing mechanism has no overturning in extreme landing conditions. The damping element damping c1 is solved by a simplified dynamic model. After solving the parameters T and $c_1$, the cardan element damping $c_2$ is calculated using the landing dynamic model, which is built by Lagrange equation. The validities of these three key parameters are tested by simulation. The results show a stable landing, when landing with the three estimated parameters T, $c_1$, and $c_2$. Therefore, the landing dynamic model and methods to estimate key parameters are reasonable, and are useful for guiding the design of the landing mechanism.

Investigation of Surface Reflection Conditions of a Substrate to Generate Diverse Wavy Structures

ZhiJun Zhao,S. H. Park(박상후),J. H. Yang(양정호) 한국정밀공학회 2015 한국정밀공학회 학술발표대회 논문집 Vol.2015 No.12월

용량형 압력 센서의 구조변형에 의한 성능향상의 기초적 연구

조지준(Zhijun Zhao),권현규(Hyunkyu Kweon),박창용(Changyong Park) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

The structured multiparameter eigenvalue problems in finite element model updating problems

Zhijun Wang,Bo Dong,Yan Yu,Xinzhu Zhao,Yizhou Fang 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.5

The multiparameter eigenvalue method can be used to solve the damped finite element model updating problems. This method transforms the original problems into multiparameter eigenvalue problems. Comparing with the numerical methods based on various optimization methods, a big advantage of this method is that it can provide all possible choices of physical parameters. However, when solving the transformed singular multiparameter eigenvalue problem, the proposed method based on the generalised inverse of a singular matrix has some computational challenges and may fail. In this paper, more details on the transformation from the dynamic model updating problem to the multiparameter eigenvalue problem are presented and the structure of the transformed problem is also exposed. Based on this structure, the rigorous mathematical deduction gives the upper bound of the number of possible choices of the physical parameters, which confirms the singularity of the transformed multiparameter eigenvalue problem. More importantly, we present a row and column compression method to overcome the defect of the proposed numerical method based on the generalised inverse of a singular matrix. Also, two numerical experiments are presented to validate the feasibility and effectiveness of our method.

A Comparative Study on the Performance of FEM, RA and ANN Methods in Strength Prediction of Pallet-Rack Stub Columns

ZhiJun Lyu,Jie Zhang,Ning Zhao,Qian Xiang,YiMing Song,Jie Li 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

The rack column is one of the essential elements in the pallet rack system. However, due to its distinctive perforation feature, it is challenging to analyze its stability using traditional theories for cold-formed steel structures. In this paper, we are interested in the comparison analysis of strength prediction on the perforated columns using fi nite element method (FEM), regression analysis (RA) and artifi cial neural network (ANN) methods respectively. First, a refi ned fi nite element (FE) model considering the perforation and nonlinearity behavior was generated and calibrated against the experimental results. Subsequently, the validated FE model was used to perform the parametric analysis for the diff erent holes in columns. Given experimental and simulated data, a regression model with an equivalent thickness was proposed for the design strength prediction of thin-walled steel perforated sections. For comparison of the RA model, two powerful tools such as the FEM and ANN are also employed to predict the design strength of diff erent perforated sections. Four indicators were used to assess the accuracy and generalization performance of the three models, including the root mean square error, the mean absolute percentage error, the correlation coeffi cient and the mean relative percentage. The obtained results show that although they both have good consistency, FEM still slightly outperforms the other two models. Since the values calculated from ANN and regression models are usually smaller than the experimental data, they are reasonably recommended as eff ective and safer design tools than FEM models from the perspective of engineering applications.

A Clustering Algorithm Based on Zone in Vehicular Ad Hoc Networks

Zhijun Yan,Yang Tao,Fangjin Zhao,QianJin He 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.12

Vehicular Ad Hoc Networks (VANET) is a wireless mobile ad hoc networks established on the inter-vehicle communication. Due to the special characteristics and the restrictions of roads, VANET shows characteristics of uneven nodes density, fast moving, high dynamic topology. So it is difficult to establish a stable link between nodes, and the reliability of data transmission declines rapidly with the increase of hops. Therefore, ensuring data reliability and rapid distribution is always a difficult point in the VANET research. Through analysis of vehicular ad hoc networks environment, we propose the node connectivity and the connectivity strength. By dividing the road environment into the segment area and the intersection area, respectively calculating and predicting the connectivity according to the road environment, we propose the zone based adaptive clustering algorithm (ZACA).

Metagenomics analysis of the gut microbiome in healthy and bacterial pneumonia forest musk deer

Wei Zhao,Ziwei Ren,Yan Luo,Jianguo Cheng,Jie Wang,Yin Wang,Zexiao Yang,Xueping Yao,Zhijun Zhong,Wei Yang,Xi Wu 한국유전학회 2021 Genes & Genomics Vol.43 No.1

Background The forest musk deer (FMD, Moschus berezovskii) is an threatened species in China. Bacterial pneumonia was found to seriously restrict the development of FMD captive breeding. Historical evidence has demonstrated the relationship between immune system and intestinal Lactobacillus in FMD. Objective We sought to elucidate the diferences in the gut microbiota of healthy and bacterial pneumonia FMD. Methods The bacterial pneumonia FMD was demonstrated by bacterial and pathological diagnosis, and the gut microbiome of healthy and bacterial pneumonia FMD was sequenced and analysed. Results There are three pathogens (Pseudomonas aeruginosa, Streptococcus equinus and Trueperella pyogenes) isolated from the bacterial pneumonia FMD individuals. Compared with the healthy group, the abundance of Firmicutes and Proteobacteria in the pneumonia group was changed, and a high level of Proteobacteria was found in the pneumonia group. In addition, a higher abundance of Acinetobacter (p=0.01) was observed in the population of the pneumonia group compared with the healthy group. Several potentially harmful bacteria and disease-related KEGG subsystems were only found in the gut of the bacterial pneumonia group. Analysis of KEGG revealed that many genes related to type IV secretion system, type IV pilus, lipopolysaccharide export system, HTH-type transcriptional regulator/antitoxin MqsA, and ArsR family transcriptional regulator were signifcantly enriched in the metagenome of the bacterial pneumonia FMD. Conclusion Our results demonstrated that the gut microbiome was signifcantly altered in the bacterial pneumonia group. Overall, our research improves the understanding of the potential role of the gut microbiota in the FMD bacterial pneumonia.

Quantitative trait locus mapping and genomic selection of tobacco (Nicotiana tabacum L.) based on high-density genetic map

Tong Zhijun,Xiu Zhihui,Ming Yao,Fang Dunhuang,Chen Xuejun,Hu Yafei,Zhou Juhong,He Weiming,Jiao Fangchan,Zhang Chi,Zhao Shancen,Jin Han,Jian Jianbo,Xiao Bingguang 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.6

Tobacco ( Nicotiana tabacum L.) is an economic crop and a model organism for studies of plant biology and genetics. As an allotetraploid plant generated from interspecific hybridization, tobacco has a massive genome (4.5 Gb). Recently, a genetic map with 45,081 single nucleotide polymorphism (SNP) markers was constructed using whole-genome sequencing data for a tobacco population including 274 individuals. This provides a basis for quantitative trait locus (QTL) mapping and genomic selection, which have been widely applied to other crops but have not been feasible in tobacco. Based on this high-density genetic map, we identified QTLs associated with important agronomic traits, chemical compounds in dry leaves, and hazardous substances in processed cigarettes. The LOD values for major QTLs were highest for agronomic traits, followed by chemical compounds and hazardous substances. In addition to the identification of molecular markers, we evaluated genomic selection models and found that BayesB had the highest prediction accuracy for the recombinant inbred line population. Our results offer new insights into the genetic mechanism underlying important traits, such as agronomic traits and quality-related chemical compounds in tobacco, and will be able to support the application of molecular breeding to tobacco.

Map-based cloning and functional analysis of the chromogen gene C in rice (Oryza sativa L.)

Shasha Zhao,Cuihong Wang,Jian Ma,Shuai Wang,Peng Tian,Jiulin Wang,Zhijun Cheng,Xin Zhang,Xiuping Guo,Cailin Lei 한국식물학회 2016 Journal of Plant Biology Vol.59 No.5

The chromogen gene C is critical for anthocyanin regulation in rice, and apiculus color is an important agronomic trait in selective breeding and variety purification. Mapbased cloning and in-depth functional analysis of the C gene will be useful for understanding the molecular mechanism of anthocyanin biosynthesis and for rice breeding. Japonica landrace Lijiangxintuanheigu (LTH) has red apiculi and purple stigmas. Genetic analysis showed that red apiculus and purple stigma in LTH co-segregated indicating control by a single dominant gene, or by two completely linked genes. Using 1,851 recessive individuals from two F2 populations, the target gene OsC was delimited to a 70.8 kb interval on chromosome 6 that contains the rice homologue of the maize anthocyanin regulatory gene C1. When the entire OsC gene and its full-length cDNA cloned from LTH were transformed into japonica cultivar Kitaake with colorless apiculi and stigmas all positive transformants had red apiculi but non-colored stigmas, validating that OsC alone was responsible for the apiculus color and represented the functional C gene. OsC was constitutively expressed in all tissues examined, with strongest expression in leaf blades. These results set a foundation to clarify the regulatory mechanisms of OsC in the anthocyanin biosynthetic pathway.